OAKLAND, Calif. (AP) Seattle Mariners ace James Paxton was replaced by Felix Hernandez in the first inning Tuesday night after being hit by a line drive on his pitching arm.

X-rays on Paxton's left arm were negative, and he was diagnosed with a forearm contusion.

Paxton allowed a leadoff home run to Oakland's Marcus Semien and struck out Matt Chapman before Jed Lowrie lined a 2-1 pitch back up the middle. Manager Scott Servais and a team trainer rushed from the dugout to check on Paxton, who seemed hesitant to move his left arm.

Paxton is 10-5 with a 3.68 ERA this season. He entered the day 11th among qualified starters with 3.6 wins above replacement, per Fangraphs.

Hernandez quickly began warming up to make his first career relief appearance following 398 starts. The 32-year-old was removed from the rotation last week amid a season full of struggles.